The present invention relates to an indicating device for indicating an activation status of an emergency slide in an aircraft, as well as to a door arrangement and an aircraft comprising such an indicating device.
In larger passenger aircraft, aircraft doors can be coupled or are connectable to an emergency slide trigger or actuation device so that, when the aircraft door concerned is opened, an emergency slide arranged thereon is triggered or actuated or deployed. For this purpose, an emergency slide safety release lever is moved before take-off and with the doors closed to an “armed” mode, in which the emergency slide is in an activated state in which the opening of the aircraft door triggers or actuates the emergency slide. After normal landing, the emergency slide safety release lever is moved to a “disarmed” mode so that a coupling with or connection to the emergency slide actuation device is disabled and the aircraft doors can be opened normally without actuating the emergency slide.
Such an emergency slide is normally in a retracted state in which the emergency slide is integrated into the aircraft door. When the emergency slide is actuated, it is extended to an extended state in which it projects outwards from the aircraft door and extends at an angle between the door opening and the ground to allow passengers to reach the ground safely.
Because emergency slides are employed in emergency situations, such as in particular after landings in which the aircraft can be damaged, it is necessary to take into account the fact that, at the time of using the emergency slide, the aircraft is not in its normal horizontal position, but is instead for example in a position in which the longitudinal axis of the aircraft is inclined or extending obliquely relative to the ground. For example, the nose of the aircraft may extend obliquely upwards. In such cases, the distance from an aircraft door to the ground can be greater than in the case of the normal horizontal position, so that an emergency slide which is designed for the normal horizontal position either does not reach the ground at all or lies at too steep an angle to allow it to be safely used.
For this reason, it is known that emergency slides—for example in the form of an optionally additionally extendable lengthening or extension portion—can be extended to two different lengths, a normal length corresponding to a horizontal position of the aircraft, and an extended length corresponding to an aircraft position in which the pitch angle exceeds a certain limit value relative to the horizontal. This in particular covers so-called “nose-up” situations, in which the nose of the aircraft points obliquely upwards. In order to realize the determination of the pitch angle required in these situations, the aircraft has several pitch angle sensors, which are installed at a central location in the aircraft and connected via cable connections to the door control devices or emergency slide actuation devices of individual doors. The door control devices or emergency slide actuation devices connected to the pitch angle sensors can thus take into account the current pitch angle during actuation or triggering of the emergency slide and control the extension length of the emergency slide accordingly. Alternatively or additionally, a warning that the emergency slide is not usable can be issued.
This arrangement is not very flexible and is associated with relatively high costs with respect to both installation and maintenance.